1. Technical Field
The present invention generally pertains to motor vehicles. More particular, the present invention pertains to pinch sensing arrangement for a motor vehicle closure panel. More specifically, but without restriction to the particular embodiment and/or use which is shown and described for purposes of illustration, the present invention relates to a pinch sensing arrangement for a motor vehicle power liftgate.
2. Discussion
In motor vehicles such as minivans, sport utility vehicles and the like, it has become common practice to provide the vehicle body with a large rear opening. A liftgate (also referred to as a tailgate) is typically mounted to the vehicle body with hinges for pivotal movement about a transversely extending axis between an open position and a closed position. Typically, the liftgate is operated manually. However, it has been heretofore proposed to provide a power drive mechanism including a reversible electric motor to operate the door. For example, such arrangements are shown in commonly assigned U.S. Pat. Nos. 5,531,498; 5,563,483; and 5,448,856, which are hereby incorporated by reference as if fully set forth herein.
During power operation of a vehicle liftgate, the liftgate may unexpectedly encounter an obstacle in its path. It is therefore desirable to cease its powered movement in that event to prevent damage to the obstacle and/or the liftgate and its power actuator. U.S. Pat. No. 5,448,856 discloses a powered liftgate system including a feature for stopping the liftgate movement upon encountering an obstacle. In this system, a powered actuator with a reversible DC motor and a worm gear driven crank arm, efficiently operates the liftgate through a roller and guide with gas spring assist. The motor current is monitored by a control circuit that interrupts the power to the actuator motor to stop the liftgate when the current exceeds a certain level as occurs when the liftgate encounters an obstacle.
While known systems for stopping liftgate movement upon encountering an obstacle have proven adequate, it has been found that certain further precautionary features with respect to the liftgate operation are desirable and that they can be accomplished in a cost effective manner.